Digestion & Nutrition

1. Digestion & Nutrition Chapter 41

2. Overview: Food processing occurs in four stages Smallmolecules Piecesof food Nutrientmoleculesenter body cells Chemical breakdown(enzymatic hydrolysis) Mechanicalbreakdown Undigestedmaterial Food 1 3 4 2 ELIMINATION INGESTION DIGESTION ABSORPTION Figure 21.2

3. Digestion occurs in specialized compartments • Food is digested in compartments housing hydrolytic enzymes • Most animals have a specialized digestive tract

4. This is called a gastrovascular cavity • Example: hydra • Relatively simple animals have a sac with a single opening Mouth Tentacle Hydrolyticenzymes Flagella Foodparticle Engulfmentof foodparticle Food(Daphnia,a waterflea) Gastro-vascularcavity Digestion infood vacuole Figure 21.3A

5. This is a tube running from mouth to anus • This tube is divided into specialized regions that process food sequentially • In most animals, the digestive compartment is an alimentary canal Crop Gizzard Esophagus Intestine Pharynx Anus Mouth EARTHWORM Wall of intestine Interior of intestine Figure 21.3B

6. Esophagus Stomach Gizzard Anus Esophagus Stomach Gizzard Intestine Crop Intestine Gastric pouches Mouth Mouth GRASSHOPPER Crop Anus BIRD Figure 21.3B (cont)

7. Ruminants such as cows process cellulose in a four-chambered stomach Intestine 3 1 Omasum Rumen Esophagus 2 Rumen Reticulum 4 Abomasum Figure 21.12B

8. Introductory Question #6 • Name the four stages of food processing. (see pg. 853). • From pg. 845, name the four types of feeders and the organism example shown. • How are the alimentary canals different in an earthworm, grasshopper, a bird, and a cow (ruminant animal). • Explain what peristalsis is and what causes it to occur. • Name the cells that line the stomach which secrete HCl and pepsin. What are fols in the stomach called? • What function do the villi serve in the lining of the intestines? Name the (3) segments of the small intestines and the (4) regions of the large intestines. • How is an essential nutrient different from any other nutrient? (pg. 849) Give three examples of a fat-soluble and three examples of a water soluble vitamin.

9. Humpback whales strain their food from seawater using large, brushlike plates called baleen • When they feed, they take in large amounts of seawater in which the fish and krill live • They must filter out the water in order to get a meal

10. In a typical day, a humpback whale’s digestive system will process as much as 2 tons of fish and krill • They store the excess energy they harvest in the form of blubber • In about 4 months, a humpback whale eats, digests, and stores as fat enough food for an entire year

11. Animals ingest their food in a variety of ways • Animal diets are highly varied • Herbivores are plant-eaters • Carnivores are meat-eaters • Omnivores eat both plants and other animals Figure 21.1A

12. Most animals ingest chunks of food Figure 21.1E

13. Some animals are suspension feeders, consuming particles from water • Some are substrate feeders, living in or on their food source Figure 21.1B, C

14. Some are fluid feeders, sucking liquids Figure 21.1D

15. Small intestine Smallintestine Stomach Cecum Colon(largeintestine) Figure 21.12A CARNIVORE HERBIVORE

16. Oral cavity Mouth Tongue Pharynx Salivaryglands Esophagus Liver Stomach Pyloricsphincter Stomach Gall-bladder Smallintestine Pancreas Smallintestine Largeintestine Rectum Figure 21.4 Anus

17. The human digestive system consists of an alimentary canal and accessory glands • When food is swallowed, it is moved through the alimentary canal by peristalsis • Peristalsis is rhythmic muscle contraction in the walls of the digestive tract • Ringlike sphincter muscles regulate the passage of food

18. The esophagus squeezes food along to the stomach • Peristalsis in the esophagus moves food boluses into the stomach Relaxedmuscles Circularmuscle layer Circularmusclescontract,constrictingpassagewayand pushingbolus down Relaxedmuscles Bolus offood Longitudinalmusclescontract,shorteningpassagewayahead of bolus Stomach Longitudinalmuscle layer Figure 21.7

19. The stomach stores food and breaks it down with acid and enzymes • The stomach mixes food with gastric juice • The gastric juice contains pepsin, which begins the hydrolysis of protein

20. Interior surfaceof stomach Pits Gastric juice(mucus, HCI,and pepsinogen) Food particle 3 Epithelium Gastricjuice Pepsinogen Pepsin (activeenzyme) 2 Mucouscells HCI Pyloricsphincter 1 Gastricgland STOMACH Chief cells Parietal cells Figure 21.8

21. Bile Liver Stomach Gall-bladder Acid chyme Bile Duodenum ofsmall intestine Pancreas Figure 21.10A

22. Enzymes from the walls of the small intestine complete the digestion of many nutrients Table 21.10

23. INTERIOR OF INTESTINE Blood vesselwith blooden route tothe liver Nutrientabsorption Nutrientabsorption Microvilli Epithelialcells Lumen Musclelayers Bloodcapillaries Circular folds Villi Lymphvessel EPITHELIALCELLS Nutrientabsorption VILLI INTESTINAL WALL Figure 21.10B

24. Bacterial Infections can cause Ulcers • New evidence suggests that a spiral-shaped prokaryote causes gastric ulcers • Helicobacter pylori growth erodes protective mucus and damages the stomach lining

25. Large Intestine Reclaims Water • Undigested material passes to the large intestine, or colon • Water is absorbed • Feces are produced Largeintestine(colon) Endof smallintestine Small intestine Rectum Anus Nutrientflow Appendix Cecum Figure 21.11

26. Small intestine Smallintestine Stomach Cecum Colon(largeintestine) Figure 21.12A CARNIVORE HERBIVORE

27. Video #5-Digestion & Fluid Balance(Ch. 41) • What organism is used by Dr. Carol Beuchat to illustrate how fluid is regulated and the role played by the urinary tract in maintaining homeostasis? (1st segment) • How is a complete digestive system different from an incomplete one? What function does each segment (region) of the digestive system have? • Name two enzymes mentioned by Dr. Sokolowski that play a role in the digestive system. How is the diet of a dog different from a cat? What are the nutritional needs for a cat and dog? What is the name of the café mentioned in the video? • The final segment discusses the role the kidneys play in maintaining homeostasis. What kind of machine is the patient connected to? 5. **Write the title for each segment and FIVE statements for each segment.

28. Digestion begins in the oral cavity • The teeth break up food • Saliva moistens it • Salivary enzymes begin the hydrolysis of starch • The tongue pushes the chewed food into the pharynx

29. TEETH Incisors Canine Premolars Molars “Wisdom”tooth Tongue Salivaryglands Opening of asalivary gland duct Figure 21.5

30. The food and breathing passages both open into the pharynx • The swallowing reflex moves food from the pharynx into the esophagus • At the same time, food is kept out of the trachea

31. Bolus of food Tongue Epiglottisup Epiglottisdown Pharynx Larynx Esophagealsphincter Larynxdown Larynxup Trachea(windpipe) Esophagus Esophagus Sphincter relaxed Sphincter contracted Sphincter contracted Figure 21.6

32. The small intestine is the major organ of chemical digestion and nutrient absorption • Alkaline pancreatic juice neutralizes stomach acids • Its enzymes digest polysaccharides, proteins, nucleic acids, and fats • Bile emulsifies fat droplets for attack by pancreatic enzymes • It is made in the liver and stored in the gall bladder

33. The lining of the small intestine is folded and covered with tiny, fingerlike villi • Villi increase the absorptive surface • Nutrients pass through the epithelium of the villi and into the blood • The blood flows to the liver • The liver can store nutrients and convert them to other substances the body can use

34. Adaptations of vertebrate digestive systems reflect diet • Herbivores and omnivores generally have longer alimentary canals than carnivores • Plant matter is more difficult to digest than meat • Nutrients in vegetation are less concentrated than in meat

35. Some mammals house cellulose-digesting microbes in the colon or cecum • The cecum is a pouch where the large and small intestines connect • Examples: horses and elephants • Other mammals re-ingest their feces to recover nutrients • Examples: rabbits and some rodents

36. A healthful diet satisfies three needs • An animal’s diet provides • fuel for its activities • raw materials for making the body’s own molecules • essential nutrients that the body cannot make

37. Chemical energy powers the body • Once nutrients are inside cells, they can be oxidized by cellular metabolism to generate energy • This energy is in the form of ATP

38. The energy a resting animal requires each day to stay alive is its basal metabolic rate (BMR) Figure 21.14

39. More energy is required for an active life • Excess energy is stored as glycogen or fat Table 21.14

40. Body Fat and Fad Diets • The human body tends to store excess fat molecules instead of using them for fuel • A balanced diet includes adequate amounts of all nutrients

41. Fad diets are often ineffective and can be harmful Table 21.15

42. A healthful diet includes 13 vitamins • Most of these vitamins function as coenzymes

43. Essential minerals are required for many body functions • Minerals are elements other than carbon, hydrogen, oxygen, and nitrogen • They play a variety of roles in the body

44. Vegetarians must be sure to obtain all eight essential amino acids • The eight essential amino acids that adults require must be obtained from food • They are easily obtained from animal protein • They can also be obtained from the proper combination of plant foods ESSENTIALAMINO ACIDS Methionine Valine (Histidine) Threonine Phenylalanine Corn Leucine Isoleucine Beans andotherlegumes Tryptophan Lysine Figure 21.16

45. Table 21.17 (Fat-soluble vitamins)

46. Table 21.17 (Water-soluble vitamins)

47. Table 21.18

48. What do food labels tell us? • Food labels provide important nutritional information about packaged foods Figure 21.19

49. Diet can influence cardiovascular disease and cancer • Choice of diet may reduce the risk of cardiovascular disease and cancer BEHAVIORALRISK FACTORS UNAVOIDABLERISK FACTORS Highbloodcholesterol Highbloodpressure Fatty diet Aging Lack ofexercise Family history CARDIOVASCULARDISEASE Smoking Being male Figure 21.20

50. Table 21.20